The overall goal of this research proposal is for Stanford University and the University of Arizona to continue their active involvement in Pediatric Oncology Group research activities. Stanford faculty have already assumed key leadership positions in POG and have a major role in the scientific and administrative aspects of the group. Moreover, Stanford has maintained an excellent performance rating in its participation in POG studies and has received a commendation for the large number of evaluable patients placed on therapeutic protocols. Specifically: (1) We plan to continue to enter Stanford patients on appropriate POG studies when they exist. The number of patient entries from Stanford has increased each year as appropriate POG studies become available. We anticipate that approximately 50 patients will be entered on front line therapeutic studies each year in addition to more than 30 patients who will be entered on POG non-therapeutic studies. (2) We anticipate that the activities of individual Stanford University participants will continue and increase during the period of this research proposal. Currrently, our faculty serve as study coordinators for five front line therapeutic studies of POG: Osteosarcoma (POG #8107), Localized Non-Hodgkin's Lymphoma (POG #8314), Ewing's Sarcoma (POG #8346), Relapsed Acute Lymphoblastic Leukemia (POG #8304) and T-cell Leukemia/Lymphoma (POG T-Cell #3). Stanford faculty also serve key administrative roles in their disciplines. Dr. Donaldson serves on the Executive Committee, Dr. Shochat serves as the Associate Chairman of the Surgery Discipline Committee, and Dr. Link serves as the Chairman of the Bone and Soft Tissue Sarcoma Committee. Thus, the Stanford faculty are in a position to influence the future direction of scientific activities of POG. (3) We anticipate that involvement of Stanford faculty in the laboratory scientific activities of POG will continue to increase. The laboratories of Drs. Link (Oncology), Roger Warnke (Pathology) and Jeffrey Sklar (Pathology) serve as immunology and genotyping reference laboratories for leukemia and lymphoma studies in POG. The laboratory of Dr. Shochat serves as one of the reference laboratories for biologic studies of neuroblastoma. (4) We anticipate that non-POG related laboratory and clinical research conducted at Stanford University will become increasingly relevant to POG activities. These activities are already of interest to POG investigators and some of these activities are already targeted for incorporation into future POG studies.